Project Summary: Cerebral vascular disease is one of the leading causes of mortality and disability worldwide. Ischemic stroke, accounting for the majority of all strokes, occurs when a blood clot blocks regional cerebral blood flow. The precipitating pathophysiological process for this catastrophic event is often platelet hyperreactivity, heightening thrombosis potential. Enhanced platelet reactivity increases the susceptibility for acute thrombotic occlusion of vessels, such as during ischemic stroke and heart attack. Over the past few years, we have developed mechanistic links between nutrients in a Western diet, gut microbiota formation of the metabolite trimethylamine N oxide (TMAO), and development of both platelet hyper-responsiveness and cardiovascular diseases. In exciting new unpublished studies, we have obtained substantial evidence indicating that the gut microbial TMAO pathway can directly contribute to the development and severity of ischemic stroke and its downstream adverse outcomes. Our proposal aims to confirm and test the hypothesis that gut microbiota, through the metaorganismal (involving both microbes and host) TMAO pathway, contributes to stroke risks. We will evaluate the role of this pathway in enhancing stroke risks by impacting platelet function, fostering worse functional impairment by augmenting cerebral inflammation via NLRP3 inflammasome activation in brain tissue. We will also examine the role of gut microbes in modulating stroke susceptibility and functional recovery post stroke onset, identify potential mechanisms contributing diet enhanced ischemic stroke risks, and explore novel therapeutic approaches targeting gut microbial contributions for prevention and treatment in cerebrovascular disease. Completion of the proposed studies will not only provide proof of concept, but also provide preclinical evidence that drugging the microbiome may serve as a novel strategy to prevent and treat cerebrovascular diseases.